Method and system for fluid mediated disk activation and deactivation

ABSTRACT

Embodiments of methods and systems for controlling access to information stored on memory or data storage devices are disclosed. In various embodiments, fluid-mediated modification of information or access to information is utilized. According to various embodiments, data storage devices designed for rotating access are described which include rotation-activated fluid control mechanisms.

RELATED APPLICATIONS

For purposes of the USPTO extra-statutory requirements, the presentapplication constitutes a continuation-in-part of U.S. patentapplication Ser. No. 11/906,579, entitled METHOD AND SYSTEM FOR FLUIDMEDIATED DISK ACTIVATION AND DEACTIVATION, naming Bran Ferren, EleanorV. Goodall, and Edward K. Y. Jung as inventors, filed 2 Oct. 2007 nowU.S. Pat. No. 7,778,124, which is currently co-pending and which is adivision of U.S. patent application Ser. No. 11/471,284, entitled METHODAND SYSTEM FOR FLUID MEDIATED DISK ACTIVATION AND DEACTIVATION, namingBran Ferren, Eleanor V. Goodall, and Edward K. Y. Jung as inventors,filed 19 Jun. 2006, now U.S. Pat. No. 7,369,471, or is an application ofwhich a currently co-pending application is entitled to the benefit ofthe filing date.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is related to and claims the benefit of theearliest available effective filing date(s) from the following listedapplication(s) (the “Related Applications”) (e.g., claims earliestavailable priority dates for other than provisional patent applicationsor claims benefits under 35 USC §119(e) for provisional patentapplications, for any and all parent, grandparent, great-grandparent,etc, applications of the Related Application(s)).

The United States Patent Office (USPTO) has published a notice to theeffect that the USPTO's computer programs require that patent applicantsreference both a serial number and indicate whether an application is acontinuation or continuation-in-part. Stephen G. Kunin, Benefit ofPrior-Filed Application, USPTO Official Gazette Mar. 18, 2003, availableat http://www.uspto.gov/web/offices/com/sol/og/2003/week11/patbene.htm.The present applicant entity has provided above a specific reference tothe application(s) from which priority is being claimed as recited bystatute. Applicant entity understands that the statute is unambiguous inits specific reference language and does not require either a serialnumber or any characterization, such as “continuation” or“continuation-in-part,” for claiming priority to U.S. patentapplications. Notwithstanding the foregoing, applicant entityunderstands that the USPTO's computer programs have certain data entryrequirements, and hence applicant entity is designating the presentapplication as a continuation-in-part of its parent applications as setforth above, but expressly points out that such designations are not tobe construed in any way as any type of commentary and/or admission as towhether or not the present application contains any new matter inaddition to the matter of its parent application(s). All subject matterof the Related Applications and of any and all parent, grandparent,great-grandparent, etc, applications of the Related Applications isincorporated herein by reference to the extent such subject matter isnot inconsistent herewith.

TECHNICAL FIELD

The present application relates, in general, to the control of access toinformation stored on memory or data storage devices. In particular, itrelates to control of access to information through modification of datastorage media.

BACKGROUND

Various methods have been used to control access to information storedon data storage devices such as CDs, DVDs, floppy disks, and so forth.Methods of controlling access to information are utilized, for variousreasons including, for example, to limit unauthorized access tocopyrighted information. Such methods may involve requiring the use ofaccess codes provided, e.g., on data storage device packaging in orderto read information from a data storage device, or erasing data orpreventing reading of data from a data storage device following readingof the device.

SUMMARY

Embodiments of methods and systems for fluid mediated regulation ofaccess to information on data storage devices are disclosed. Features ofvarious embodiments will be apparent from the following detaileddescription and associated drawings.

BRIEF DESCRIPTION OF THE FIGURES

Features of the invention are set forth in the appended claims. Theexemplary embodiments may best be understood by making reference to thefollowing description taken in conjunction with the accompanyingdrawings. In the figures, like referenced numerals identify likeelements.

FIG. 1 illustrates a system including a disk drive;

FIG. 2 illustrates a computer system;

FIG. 3 illustrates parameters relating to rotation of a disk;

FIGS. 4A-4C illustrate angular velocity, its derivative, and its square,respectively;

FIG. 5 depicts a disk having a rotation activated fluid releasemechanism;

FIG. 6 depicts fluid release devices configured to release fluid inresponse to angular acceleration or deceleration;

FIGS. 7A and 7B depict a fluid release mechanism;

FIG. 8 illustrates a disk having machine readable data stored thereon;

FIG. 9 illustrates a disk having machine readable data stored thereon;

FIG. 10 illustrates a capillary valve mechanism;

FIG. 11 illustrates a further valve mechanism;

FIG. 12 illustrates a microvalve;

FIGS. 13A and 13B illustrate degradation of a portion of a data storagemedium produced by introduction of a fluid;

FIGS. 14A and 14B illustrate degradation of data produced byintroduction of a fluid;

FIGS. 15A and 15B depict blocking of reading of data by a fluid;

FIGS. 16A and 16B illustrate degradation of a portion of a data storagemedium produced by release of a fluid;

FIGS. 17A and 17B illustrate degradation of data produced by release ofa fluid;

FIGS. 18A and 18B illustrate optical interference with data readingproduced by release of a fluid;

FIGS. 19A and 19B depict degradation of a portion of a data storagemedium produced by a fluid acting in combination with an additionaldegradation inducing factor;

FIGS. 20A and 20B depict degradation of data produced by a fluid actingin combination with an additional degradation inducing factor;

FIGS. 21A and 21B depict a fluid blocking degradation of data by anadditional degradation inducing factor;

FIG. 22 depicts a disk having a rotation activated fluid releasemechanism;

FIG. 23A-23C illustrate exemplary patterns of angular velocity, itsderivative, and its square, respectively;

FIG. 24A-24C illustrate exemplary patterns of angular velocity, itsderivative, and its square, respectively;

FIG. 25 illustrates a data storage device having a plurality ofcentrifugally activated fluid release mechanisms;

FIGS. 26A and 26B depict an embodiment of a fluid switch;

FIGS. 27A and 27B depict another embodiment of a fluid switch;

FIGS. 28A and 28B illustrate blocking of reading of data by closing aswitch;

FIGS. 29A and 29B illustrate producing destruction of data by closing aswitch;

FIGS. 30A and 30B illustrate producing modification of data by closing aswitch;

FIG. 31 illustrates a data storage device with a fluid release mechanismactivatable over multiple uses;

FIGS. 32A and 32B depict a rotation activatable switch;

FIG. 33 illustrates different orientations of rotation activatableswitches;

FIG. 34 is a schematic diagram of a system including a data storagedevice;

FIG. 35 is a flow diagram of a method of activating a rotationactivatable control mechanism in association with reading data;

FIG. 36 is a flow diagram of a method of activating a rotationactivatable control mechanism in association with reading data;

FIG. 37 is a flow diagram of a method of activating a rotationactivatable control mechanism in association with reading data;

FIG. 38 is a flow diagram of a method of activating a rotationactivatable barrier in association with reading data;

FIG. 39 is a flow diagram of a method of controlling access to data on adisk;

FIG. 40 is a flow diagram of a method of controlling access to data on adisk;

FIG. 41 is a flow diagram of a method of manufacturing a data storagedevice;

FIG. 42 is a flow diagram of a method of operating a disk drive; and

FIG. 43 is a flow diagram of a method of configuring a disk drive foruse with a rotation-sensitive disk.

DETAILED DESCRIPTION

FIG. 1 illustrates a system 10, which may be a computer system or othersystem that includes a data storage device 24 configured for rotatingaccess. System 10 includes a processor 12, system memory 14, one or moreI/O devices 16, and disk drive 22, which is configured to receive a diskshaped data storage device 24. The system may also include a powersupply, not shown. Data, power and control signals may be transferredbetween system components via data bus 26. Processor 12 may be amicroprocessor. In this example, and in general, data storage device 24may be a CD, DVD, floppy disk, or any of various other data storagedevices configured for rotating access. Such data storage devices arefrequently disk shaped, but the invention is not limited to use withdisk shaped data storage devices.

As a specific example of the system depicted in FIG. 1, FIG. 2illustrates a computer system 28. Computer system 28 includes aprocessor 12, system memory 14, system bus 26, output device 32, whichin this example is a monitor, and input device 34, which in this exampleis a keyboard. System memory 14 includes read-only memory 36 andrandom-access memory 38. Device driver 40 is stored in random-accessmemory 38. Device driver 40 is used to control disc drive 30. Interface42 provides an interface between the computer system 28 and disk drive30. Control line 60 and data line 62 provide for the transfer of controland data signals between system 28 and disk drive 30. Disk drive 30includes receptacle 56, which is adapted to receive disk 24. Disc 24 isrotated by motor 46. Positioner 48 adjusts the position of the read head50 with respect to disk 24.

FIG. 3 illustrates parameters associated with rotation of disk 24, whichmay be a disk shaped data storage device 24. Disk 24 may have a radiusr. If disk 24 is rotated with angular velocity ω, for example in acounterclockwise direction as depicted in FIG. 3, a particle at theperiphery of the disc will move with a tangential velocity V_(T). Thecentripetal acceleration a_(c) indicated by the grey arrow, will be ω²r.FIGS. 4A-4C depict the relationship between angular velocity, ω, anddω/dt and ω², which are proportional to angular acceleration, andcentripetal acceleration, respectively. Values of ω, dω/dt and ω²depicted in FIGS. 4A-4C are obtained when a disk that is initially atrest is rotated, increasing the rate of rotation over a first timeperiod 76 until a constant angular velocity is reached, then held at aconstant angular velocity for a second time period 78, and thengradually brought to rest again over a third time period 80. This isonly one example of many possible disk rotation patterns. In FIG. 4A,the angular velocity ω, represented by trace 70, is increased from zeroover first time period 76 of duration t₁ until a velocity ω₁ is reached,held constant at velocity ω₁ over second time period 78 having aduration t₂, and then decelerated back to zero angular velocity overthird time period 80, also of duration t₁. The corresponding angularacceleration, dω/dt, represented by trace 72 in FIG. 4B, has a value ofω₁/t₁ during first time period 76 and a value of −ω₁/t₁ during thirdtime period 80, and is otherwise zero. The centripetal accelerationexperienced by a particle at a given location on the disk will be equalto square of the angular velocity multiplied by the distance of thelocation from the center of rotation. Thus, for a particle at theperiphery (at a distance r from the center of rotation), the centripetalacceleration will be ω²r. Trace 74 in FIG. 4C represents ω², which isproportional to the centripetal acceleration. As can be seen in FIG. 4C,ω² increases non-linearly over first time period 76, is constant duringsecond time period 78, and decreases non-linearly over third time period80. As a disk rotates, a particle (which may be fluid or liquid) in oron the disk will experience an apparent “centrifugal force”,proportional to the centripetal acceleration and operating in theopposite direction, driving the particle toward the periphery of thedisk. During periods of angular acceleration and deceleration (e.g.,time periods 76 and 78 in FIGS. 4A-4C), a particle in or on the diskwill experience an angular force proportional to the angularacceleration dω/dt and of the same sign, with the direction of theangular force depending on whether the disk is accelerating ordecelerating.

FIG. 5 depicts an embodiment of a disk 100 having a rotation activatedfluid release mechanism 101. Fluid release mechanism 101 may includefluid chamber 102. Fluid chamber 102 may contain a degradation inducingfluid 104, which is retained in chamber 102 by pressure sensitive fluidbarrier 106. A degradation sensitive region 110 located within a chamber108 may be located radially outward of fluid chamber 102. When disk 100is rotated, centrifugal force F_(C), indicated by a black arrow, movesfluid 104 toward fluid barrier 106. The fluid release mechanism in FIG.5 is sensitive to centripetal acceleration (‘centrifugal force’).

By changing the orientation of the fluid release mechanism, it could bemade sensitive to forces associated with angular acceleration, ordeceleration. Such device may be obtained, for example, by orienting afluid release mechanisms 122 and 124 on disk 120 as depicted in FIG. 6.A positive angular velocity ω, is obtained when the direction ofrotation of disk 120 is as indicated by the gray arrow. Angularacceleration will produce inertial force F_(A) in fluid in fluid releasemechanism in the direction indicated by the black arrow. Angulardeceleration will produce inertial force F_(D) in fluid releasemechanism 122, in the direction indicated by the black arrow. Thus,fluid will be released from fluid release mechanism 122 during angularacceleration of sufficient magniture, and fluid will be released fromfluid release mechanism 124 during angular deceleration of sufficientmagnitude.

As depicted in FIG. 7A, F_(C), drives fluid 104 against fluid bather 106to produce a pressure differential across fluid barrier 106, such thatthe pressure P₁ on the radially inward side of fluid barrier 106 (i.e.,the side toward fluid chamber 102) is higher than the pressure P₀ on theradially outward side of fluid barter 106 (i.e., the side towarddegradation sensitive region 110). Air vents 112 and 114 may be includedto permit the movement of fluid within chamber 102 and 108. When thepressure differential becomes large enough, fluid barrier 106 mayrupture, break down, or otherwise release fluid 104 so that it movesinto chamber 108, where it may cause degradation of degradationsensitive region 110. FIG. 7B depicts the fluid barrier in ruptured form106′. In this example, fluid barrier 106 is a frangible fluid barrier.Pressure sufficient to permit movement of fluid from the reservoir maybe obtained by spinning the substrate. If an optical disk is used, insome embodiments pressure sufficient to permit movement of fluid may beobtained by spinning the substrate in an optical disk drive at normalread speeds, while in other embodiments, pressure across the pressuresensitive barrier sufficient to permit movement of fluid from thereservoir may be obtainable by spinning the substrate in an optical diskdrive at speeds above normal read speeds. Similarly, if the data storagedevice is a magnetically readable disk, pressure across the pressuresensitive barrier sufficient to permit movement of fluid from thereservoir is obtainable by spinning the substrate in a magnetic diskdrive at normal read speeds in some embodiments, while in otherembodiments pressure across the pressure sensitive barrier sufficient topermit movement of fluid from the reservoir is obtainable by spinningthe substrate in a magnetic disk drive at speeds above normal readspeeds.

Machine readable data is commonly stored in a binary code, which may bestored in various materials that can exist in two different states. Forexample, data may be stored in a pattern of electrical potentials,magnetized regions, optically transmissive regions, or opticallyreflective regions, among others, as known or as may be devised by thoseof skill in the relevant arts. A degradation sensitive region of a datastorage device may include any portion of the data storage device thatmay be modified in some way to render information stored in the regioninaccessible or unusable in some way. ‘Degradation’ may includemodification of data stored in a data storage medium. A first state inthe data storage medium may represent a ‘1’, while a second state mayrepresent a ‘0’. Various other coding schemes may be used, which mayinclude more than two different states. Modification of data values mayinclude setting all data values to a ‘1’, setting all data values to a‘0’, resetting data values to a random value or to some pattern (e.g.,alternating ‘1’s and ‘0’s), or reducing the signal-to-noise ratio of thestored data. Degradation may include destruction of the data storagemedium so that no data may be stored therein. Degradation of adegradation sensitive region may include destruction or modification ofa substrate or coating located adjacent or near a data storage medium.If data is read optically, with the use of light transmitted through atransparent substrate, reading of data may be blocked, for example, bymodifying or degrading the substrate to block or hinder transmission oflight through the substrate.

In some embodiments, degradation may affect all or most of the datastored on a disk, with degradation considered to include destruction ormodification of data, destruction or modification of a data storagemedium, or destruction or modification of a substrate or coating layeradjacent or near a data storage medium. In other embodiments, all orportions of data on a data storage device may be rendered inaccessibleby degrading a subset of data on the data storage device that containsinformation necessary for reading data stored on other parts of the datastorage device. For example, as depicted in FIG. 8, data of interest(which might be, for example, a computer program or an audio or videodigital recording) may be distributed to multiple locations on datastorage device 150. In order to retrieve the data of interest in usableform, it may be read from the appropriate location in the appropriateorder, as specified by index information stored in disk region 152. Inthe present exemplary embodiment, disk region 152 may specify that datamay be read from first data region 154, second data region 156, thirddata region 158, fourth data region 160, fifth data region 162 and sixthdata region 164, in that sequence. Thus, in order to render the datastored in first through sixth data regions 154 through 164 unusable, itmay be sufficient to render data stored in disk region 152 inaccessible,for example by degradation of data, data storage medium, and/orsubstrate, as described above.

Various other methods of controlling access to data on a disk by causingdegradation of a limited portion of the disk may also be used. Anotherexample is depicted in FIG. 9. In FIG. 9, disk 170 includes data region172 containing data of interest in encrypted form. Key region 174contains a decryption key that may be used to decrypt data stored indata region 172. Degradation of key region 174 may thus be sufficient toblock access to data stored in data region 172.

In some embodiments, an index or key portion of data may containinformation necessary for reading data from other regions of the datastorage device. Degradation of index or key data thus causes“deactivation” of the data storage device. In other embodiments, anindex or key region may contain a code that blocks reading of data fromthe disk, e.g., because after the information has been read from thedisk, reading is discontinued by the disk drive or program controllingreading of data from the disk. Degradation of such key or indexinformation then “activates” or enables reading of data from the datastorage device. As a further alternative, the key or index informationmay activate or deactivate selected portions of the data storage device,so that (for example) different data may be read from the data storagedevice on the first reading than on the subsequent readings.

FIGS. 5, 7A and 7B depict exemplary embodiments in which a pressuresensitive fluid barrier 106 is a frangible barrier. Various otherbarrier or valve structures that open in response to fluid pressure,including but not limited to capillary breaks, hydrophobic breaks, orhydrophobic valves, may also be used. FIGS. 10 and 11 depict additionalexemplary fluid barriers. In FIG. 10, a first chamber 200 and secondchamber 202 are separated by a restricted diameter valve region 204.Valve region 204 may be any of various types of passive or capillaryvalves, for example, as described in “Design and Fabrication of PolymerMicrofluidic Platforms for Biomedical Applications,” Madou et al., ANTEC2001, pp. 2534-2538; “Design Analysis of Capillary Burst Valves inCentrifugual Microfluidics,” Zeng et al., Tech. Proc. of μTAS, May 2000,Enschede, The Netherlands, pp. 493-496; U.S. Pat. No. 6,591,852 and U.S.Pat. No. 6,296,020, all of which are incorporated herein by reference intheir entirety. Such valves may block the movement of fluid unless asufficiently high pressure differential is applied across therestriction. In some embodiments, if an aqueous fluid is used, andchambers 200 and 202 and valve regions 204 may be formed in ahydrophobic material, an abrupt reduction in channel diameter, as occursat entrance 206 of valve region 204, may obstruct the flow of fluid.Alternatively, a capillary break, or channel widening, as at exit 208 ofvalve region 204 may function as a passive or capillary valve. Asdepicted in FIG. 11, a valve region 224 between chambers 220 and 222 mayalso be formed by the application of a surface treatment 226 to theinterior of valve region 224. For example, a hydrophobic surfacetreatment 226 may be used to obstruct the flow of an aqueous fluidthrough valve region 224, while a hydrophilic surface treatment mayobstruct the flow of a non-polar fluid through valve region 224.Alternatively, surface treatment 226 may include a dried material that,when dissolved in the fluid, modifies the surface tension of the fluid.

Different types of microvalves may be used in various embodiments. Insome embodiments, micromechanical valves may include elements thatphysically block a fluid channel, and are controllable by various means.Such micromechanical valves may include, for example colloidal orpolymeric valve elements that can be moved or changed in size orconfiguration to open the valve. A few examples are described, forexample in U.S. Pat. Nos. 6,837,476, 6,802,489, and 6,793,753, all ofwhich are incorporated herein by reference in their entirety FIG. 12depicts in schematic form a fluid chamber 240 separated from adegradation sensitive region 242 by a microvalve 244.

Degradation of data may take place by various mechanisms, and mayinclude degradation or modification of data, data storage medium, and/orsubstrate. Degradation of the data storage medium may include one ormore of destruction of the data storage medium, modification of the datastorage medium, modification of data stored in the data storage medium,and modification of signal-to-noise ratio of data stored in the datastorage medium. Degradation may take place directly in response to adegradation inducing influence, or, it may be initiated by a degradationinducing influence but continue to completion after removal of thedegradation inducing influence. This may be the case, for example, ifthe degradation inducing influence provides input of an activationenergy sufficient to overcome an energetic barrier and set off achemical process that proceeds without further input of energy onceinitiated. A degradation inducing influence may produce degradationdirectly, or may function as an intermediary to enable or initiateaction by a direct degradation inducing influence. Degradation mayinclude various combinations of two or more degradation mechanisms, andin some embodiments may be produced by synergistic or cooperativeeffects of two or more degradation inducing or producing factors orinfluences. In general, release of fluid may produce (directly orindirectly) a modification of a modifiable feature on a data storagedevice. Examples of modifiable features include, but are not limited to,mechanical properties, optical properties, electrical properties,magnetic properties, or chemical properties. FIGS. 12-20 provideexamples of a number of fluid-induced degradation mechanisms, caused byintroduction of fluid into a region of a data storage device or removalof fluid from a region of a data storage device.

In FIG. 13A, a portion of a data storage device 250 is depicted. Datastorage device 250 includes a substrate 252 and a data storage medium254 storing binary data 256, represented by a pattern of black blocksrepresenting one of two states of data storage medium 254. A channel 258runs through substrate 252. Channel 258 is empty in FIG. 13A. In FIG.13B, fluid 259 has filled channel 258. The presence of fluid 259 causesdegradation substrate 252 to form degraded substrate 252′, through whichdata 256 cannot be read. Degradation of substrate 252 may include achange in a material property of the substrate or a change in shape orconformation of the substrate material, such as thickness or surfacetexture. Material properties may include optical properties such asreflectivity, index of refraction, transmissivity, light scattering,electrical properties, magnetic properties, and so forth. Modificationsto material properties, shape, or conformation may be caused by a phasechange, chemical reaction, melting, etching, corrosion, etc. of thesubstrate material due to exposure to fluid. Many specific combinationsof substrate material and degradation inducing fluid may be used;examples include the combination of water (or other aqueous fluids) withwater-absorbing polymers that expand upon exposure to water; thecombination of an oxidation-inducing fluid in combination with asubstrate containing colorless compounds that may be oxidized to formcolored compounds, such as indigo carmine, methylene blue, thionin,gallocyanine, among others, as discussed in U.S. Pat. No. 6,011,772,which is incorporated herein by reference.

FIGS. 14A and 14B illustrate a portion of a data storage device 260.Data storage device 260 includes a substrate 262 and a data storagemedium 264 storing binary data 266, again represented by a pattern ofblack blocks representing one of two states of data storage medium 264.A channel 268 runs between substrate 262 and data storage medium 264.Channel 268 is empty in FIG. 14A. In FIG. 14B, fluid 269 has filledchannel 268. The presence of fluid 269 causes degradation of data 266stored in data storage medium 264. Degraded data 266′ is readable butdoes not contain the correct information. Modification or destruction ofdata may be caused by a phase change or chemical produced in the datastorage medium due to exposure to the degradation inducing fluid. Forexample, in optical disks, a reflective layer of metallic aluminum maybe used as a data storage medium. Exposure of metallic aluminum to anaqueous salt solution, for example, may result in oxidation of thealuminum to form non-reflective hydroxy salts.

FIGS. 15A and 15B illustrate a portion of a data storage device 270,which includes a substrate 272, data storage medium 274 containing data276, and fluid channel 278. Data is read through substrate 272 andchannel 278 when channel 278 is empty. Reading could be by variousmeans, for example, optically, magnetically, electrically, and so forth.As shown in FIG. 15B, when fluid 279, which is opaque ornon-transmissive to the read signal, fills channel 278, reading of datathrough substrate 272 is blocked. Fluid 279 may absorb, reflect,scatter, or otherwise interfere with a signal used to read data 276.Fluids may absorb, reflect, scatter, or otherwise be non-transmissive toelectrical signals, optical signals, magnetic signals, or various othersignals used to read data 176 from data storage medium 274. Fluids thatmay be used to block optical reading of data include various dyesolutions. Fluids containing ferric and/or ferrous materials may be usedto block magnetic reading of data include.

FIGS. 16A and 16B illustrate degradation of a region of a data storagedevice 280 produced by release of a fluid from the region. Data storagedevice 280 includes substrate 282, data storage medium 284 containingdata 286, and channel 288 containing fluid 289. Data 286 may be readthrough substrate 282 and fluid 289. In FIG. 16B, fluid 289 has beenrelease from channel 288 so that it is empty (i.e., it fills with airthat enters via an air channel when fluid 289 is released). In theabsence of fluid 289, the substrate degrades to degraded substrate 282′,which is non-transmissive to the read signal and thus prevents readingof data 286. Substrate 282 may degrade when exposed to one or morecomponents of air, or it may be an unstable material that is preservedby the presence of the fluid but degrades with the release of fluid fromchannel 288. Possible combinations of substrate and fluid that exhibitthese properties include substrates that include a colorless compoundthat is oxidized upon exposure to air to form a colored compound (e.g.methylene blue, thionin, indigo carmine, or gallocyanine) used incombination with an oxidation-protective fluid such as a buffer.

Similarly, FIGS. 17A and 17B illustrate degradation of data produced byrelease of a fluid from a region 290 of a data storage device. Fluidchannel 298 is formed between substrate 292 and data storage medium 294,which contains data 296. Fluid 299 is contained in fluid channel 298. InFIG. 17B, fluid 299 has been released, leaving channel 298 empty. In theabsence of fluid 299, data 296 stored in data storage medium 294 ismodified or degraded to degraded data 296′, which may be readable butdoes not contain usable information. Possible combinations of datastorage medium and fluid that result in such a degradation patterninclude metallic data storage media used in combination with anoxidation-protective fluid.

FIGS. 18A and 18B illustrate optical interference with data readingproduced by release of a fluid. In FIG. 18A, portion 300 of a datastorage device includes a substrate 302, data storage medium 304containing data 306, and channel 308 containing fluid 309. Fluid 309 mayhave an index of refraction that matches that of substrate 302, topermit optical reading of data 306. When fluid 309 is released fromchannel 308, as depicted in FIG. 18B, a mismatch between the index ofrefraction of substrate 302 and air contained in channel 308 may hinderreading of data 306.

In FIGS. 19A and 19B, a portion of data storage device 320 is depictedwhich includes substrate 322, data storage medium 324, and channel 328between substrate 322 and data storage medium 324. Data storage medium324 contains data 326. Data storage device 320 is exposed to anadditional degradation inducing factor or influence 330, which may be,for example, heat, light, other forms of electromagnetic radiation,pressure, a magnetic field, or an electrical field. Additionaldegradation inducing factor 330 has no effect by itself, but, asdepicted in FIG. 19B, when fluid 329 is introduced into channel 328,fluid 329 and additional degradation inducing factor 330 actsynergistically or in cooperation to produce degradation of substrate322 to degraded form 322′, to block reading of data 326. Additionaldegradation inducing factor 330 may function to provide activationenergy for a reaction involving fluid 329 and substrate 322. Forexample, fluid 329 may contain a reactant that will participate in areaction (e.g., a reduction or oxidation reaction) upon exposure to anadditional degradation inducing factor as listed above to produce achange in color or dimension of substrate 322.

FIGS. 20A and 20B depict a portion of data storage device 340, whichincludes substrate 342 and data storage medium 344, which containsstored data 346 and has a channel 348 running through it. Data storagemedium 344 is exposed to additional degradation inducing factor 350.Additional degradation inducing factor 350 has no effect until, as inFIG. 20B, fluid 352 is introduced into channel 348. Additionaldegradation inducing factor 350 may be, for example, heat, light, otherforms of electromagnetic radiation, pressure, a magnetic field, or anelectrical field. Fluid 352 and additional degradation inducing factor350 act in combination to produce degradation of data 346 to degradedform 346′. As discussed above, additional degradation inducing factor350 may provide activation energy to a chemical reaction between fluid352 and data 346 stored in data storage medium 344.

In another embodiment, a fluid may be released from a region of a datastorage device to permit exposure of a degradation sensitive region todegradation by an additional degradation inducing factor. In FIG. 21A, aportion of data storage device 360 includes substrate 362 and datastorage medium 264 containing data 366. Fluid 370 contained withinchannel 368 may block exposure of data storage medium 364 to degradationinducing factor 372. As shown in FIG. 21B, when fluid is released fromchannel 368, data storage medium 364 is exposed to degradation inducingfactor 372, which converts data stored therein to a degraded form 366′.For example, degradation inducing factor 372 may be light, and fluid 370may be a fluid that blocks transmission of light, examples of which areprovided above. As an alternative, degradation inducing factor 372 maybe a magnetic field, and fluid 370 may be a fluid that blocks orotherwise modifies transmission of the magnetic field, for example, afluid containing ferrous and/or ferric materials Various combinations ofdegradation inducing factors and blocking fluids may be designed for usein various embodiments, by a practitioner of skill in the relevant arts.

The specific type of fluid that may produce degradation of substrate,data storage medium, or data, as illustrated in the forgoing examples,will depend upon the materials used as substrate and data storagemedium, and the method by which data is read. Fluids may have variouschemical, optical, electrical, physical, thermal, and/or otherproperties selected to work in combination with data storage devicematerials, and, in some embodiments, with additional degradationinducing influences, to produce a desired effect. Similarly, theadditional degradation inducing influence may be selected based uponchoice of substrate, data storage medium, and fluid type. Exemplarycombinations have been presented. Additional combinations will beapparent to the practitioner of skill in the art, and the foregoingexamples are not intended to be limiting. As used herein, the term‘fluid’ may include a variety of materials having fluid-like properties,including but not limited to liquids, gases, powders, and variouscombinations thereof. The term fluid encompasses both homogeneous andinhomogeneous materials or mixtures. Combinations may include emulsions,suspensions, and slurries. In some cases, the fluid may be a combinationmade up of a fluid or fluid-like carrier material and an activecomponent carried in the carrier material. The carrier material mayconfer upon the mixture its fluid properties, while the active componentmay confer up on the fluid its degradation-inducing ordegradation-preventing properties.

As noted previously, release of fluid may cause degradation or othermodification of a disk immediately upon its release, or it may initiatea process which may take place over some period of time followinginitiation (by selecting the process appropriately, the process may takeplace over seconds, minutes, hours, days or weeks, depending upon theparticular chemical processes involved). If degradation is notimmediate, it may be satisfactory to initiate the degradation processbefore any data has been read from the disk, and any fluid releasemechanism that is activated at some point during a read of data from thedata storage medium may be sufficient. If, however, fluid releaseproduces immediate data degradation when it enters the fluid sensitiveor fluid responsive region of the data storage medium, then fluidrelease must be controlled in such a manner that it occurs only afterdata has been read from the data storage device. If the fluid causesdegradation of only key or index data, then it may be acceptable ordesirable to release fluid after key or index data has been read fromthe disk, but possibly prior to reading of data from other areas of thedisk. In various embodiments, it may be desirable to control the timingof the release of fluid.

FIG. 22 is an exemplary embodiment of a data storage device configuredsuch that fluid released in such a way that it enters a fluid responsiveregion following a single read of data from the device. FIG. 22 depictsa data storage device 400 that includes a disk-shaped substrateconfigured for rotating access. Machine-readable data may be stored in adata storage medium carried by the substrate. The data storage devicealso includes a fluid release device and associated fluid circuitconfigured to deliver fluid to a portion of the data stored on the datastorage device following a single use of the device. Data storage device400 includes reservoir 404, which is adapted to contain fluid 406. Datastorage device 400 also includes fluid responsive or fluid sensitiveregion 402, which is configured to receive fluid from reservoir 404 andupon receipt of fluid to undergo a change, which may include any ofvarious types of changes or modifications as depicted in the previousexamples. A pressure sensitive barrier 408 between reservoir 404 andfluid responsive region 402 is adapted to prevent flow of fluid fromreservoir 404 to fluid responsive regions 402 if the pressure dropacross pressure sensitive barrier 408 is below a first pressuredifference, and to permit flow of fluid from reservoir 404 to fluidresponsive region 402 if the pressure drop exceeds the first pressuredifference. First radial channel segment 410 extends radially outwardfrom pressure sensitive barrier 408 and is adapted to receive fluid fromreservoir 404. Connecting channel segment 412 is adapted to receivefluid from first radial channel segment 410. Second radial channelsegment 414 extends radially inward from connecting channel segment 412to fluid responsive region 402, and is adapted to deliver fluid fromconnecting channel segment 412 to fluid responsive region 402.

In use, fluid 406 moves from reservoir 404 when the centrifugal force issufficient to cause barrier 408 to fail, and moves down first radialchannel segment 410 to connecting channel segment 412, driven bycentrifugal forces. Fluid 406 may move into connecting channel segment412 driven by angular acceleration forces, or may be drawn in bycapillary forces. Fluid may move through second radial channel segment414 to fluid responsive region 402 when centrifugal forces decrease to alevel where they are surpassed by capillary forces in second radialchannel segment 414 and fluid responsive region 402. Centrifugal forceswill initially reach the level needed to cause fluid to flow throughpressure sensitive barrier 408 when the disk rotates as reading of thedisk is initiated, and centrifugal forces may decrease sufficiently toallow fluid to flow into second radial channel segment 414 and to fluidresponsive region 402 when the disk decelerates at the end of reading.

In some embodiments, the pattern of disk rotation that occurs during asingle use or reading of a disk may not match the simple accelerationpattern depicted in FIGS. 4A-4C, in which acceleration to a constantvelocity is eventually followed by deceleration back to rest. If thedisk is read in sequence, in some cases the angular velocity may bevaried as a function of distance of the read head from the center of thedisk, in order to provide a constant linear velocity at the position ofthe read head. Moreover, depending on how the data is distributed on thedisk, reading may involve multiple accelerations and decelerations. Forexample, the angular velocity, ω, and corresponding dω/dt and ω², may beas depicted in FIGS. 23A-23C. In order to control the timing of fluidrelease with respect to reading of some or all of the data from thedisk, the expected pattern of disk rotation during reading of the diskmay be taken into account, the inertial forces due to angular andcentripetal acceleration determined, and pressure sensitive barrier andfluid channels on the disk must be configured appropriately. Theorientation and break pressure of each pressure sensitive barrier may beselected according to the anticipated rotation pattern, and capillaryforces produced by fluid channels such as second radial channel segment414 in FIG. 22, which may depend upon channel dimensions and combinationof channel material and fluid properties, may be selected to operate incooperation with inertial forces.

FIGS. 23A-23C illustrate ω, and corresponding dω/dt and ω², in a casewhere the data storage medium is driven by a motor that produces aconstant torque, and hence constant acceleration or deceleration. Asshown in FIG. 23A, angular velocity ω, represented by trace 419,increases linearly over time interval 422 to a first constant velocityat peak 424. ω decreases linearly over time interval 426 to a secondconstant velocity 428, increases again over time interval 430 to a thirdconstant velocity, 432, decreases over time interval 434 to fourthconstant velocity 436, and increases again over time interval 438 toreach fifth constant velocity 440, which is the same as third constantvelocity 432. Finally, ω decreases over time interval 442 until thesubstrate is at rest. Corresponding values of dω/dt and ω² are indicatedby traces 420 and 421 in FIGS. 23B and 23C, respectively. It can be seenfrom FIG. 23B that over time intervals 422, 430, and 438, the angularacceleration dω/dt is of constant amplitude, but the duration of theacceleration pulses varies depending on the corresponding change inangular velocity. Similarly, over time intervals 426, 434, and 442,dω/dt is of constant negative amplitude, but the duration of thedeceleration pulses varies depending on the corresponding change inangular velocity. The start of disk use could be detected, for example,by providing a fluid release mechanism that was sensitive tolong-duration angular acceleration pulse 444. Similarly, the end of diskuse could be detected by providing a mechanism sensitive tolong-duration angular deceleration pulse 446. Centrifugal forces,proportional to ω², may show peaks, e.g., 446, 450, and 458 as depictedin FIG. 23C, that may be differentiated by duration-sensitivemechanisms, offering further possibility for controlling the timing ofdisk activation or deactivation.

FIGS. 24A-24C depict a further pattern of angular velocity ω, indicatedby trace 530 in FIG. 24A. The corresponding pattern of angularacceleration dω/dt is indicated by trace 532 in FIG. 24B, and thecorresponding value of ω², proportional to the associated “centrifugalforce” is represented by trace 534 in FIG. 24C. In the example of FIGS.24A-24C, the magnitude of angular acceleration dω/dt (and the associatedinertial forces) is variable, so different segments of disk use may becharacterized by differences in amplitude as well of duration in angularacceleration forces. Note that angular acceleration peaks 536 and 540differ in both amplitude and duration; similarly, angular decelerationpeaks 538 and 544 differ in amplitude and duration. Centrifugal forces,proportional to ω², as indicated by trace 534 in FIG. 24C, similarlyshow differences in amplitude and duration (e.g., peaks 546 and 548)that may be detected by appropriately configured fluid release devices.

In some embodiments, it may be desirable to produce activation of afluid release mechanism at a particular time during a use of a datastorage device. This can be accomplished easily in the case that angularacceleration only occurs at the beginning of each use, and angulardeceleration occurs only at the end of each use (as depicted in FIGS.4A-4C) by orienting fluid release devices so that they are sensitive toangular acceleration or deceleration, as desired. If multiple angularaccelerations and decelerations occur during a single use, as depictedin FIGS. 23A-23C and 24A-24C, then it may be possible to set a thresholdvalue for response of a fluid release device to angular acceleration, sothat fluid may be released during the highest acceleration conditionthat occurs during use of the data storage device. Similarly, athreshold value may be set for angular deceleration, so that fluid maybe released during the highest deceleration condition that occurs duringuse of the data storage device. In some embodiments, amplitude of diskacceleration may not provide a sufficient basis for controlling timingof fluid release during use of the disk, but duration of accelerationmay be used for identifying a time when fluid should be released. Forexample, if a constant torque motor is used, a long acceleration periodwill be necessary to bring the disk up to speed initially, and a longdeceleration period will be necessary to bring the disk back to rest atthe end of a use, but changes in speed during a single use may involveshorter periods of acceleration or deceleration. Therefore, thebeginning and end of a single use may be identified through the use of amechanism that is responsive to acceleration or deceleration,respectively, of a specified duration. Fluid valves that are sensitiveto the duration of exposure to rotational forces may be used.

Another method for controlling timing of fluid release during use of adata storage device is to combine fluid release with exposure of afluid-sensitive portion of the data storage device to an additionaldegradation inducing influence. Degradation inducing influence mayinclude heat, light, other forms of electromagnetic radiation, pressure,a magnetic field, or an electrical field. The use of fluid release incombination with an additional degradation inducing factor is shown inFIGS. 20A and 20B or FIGS. 21A and 21B. In these examples, degradationis produced by combining release of a fluid, which may occur at somepoint during a use of a device, with an additional factor. For example,if the additional factor is a beam of light from a read head, the diskmay be configured so that the degradation sensitive region is located ona portion of the disk that is exposed to light from the read head onlyonce during use of the device, e.g. at the end of use when the read headpasses over the edge of the disk as it returns to its ‘parked’ position.Providing fluid is release at some time during use of the device, thedegradation sensitive portion of the disk will respond when it isexposed to light, which occurs at a well-defined time during use of thedisk. Accordingly, the degradation is produced or initiated at awell-defined time even if the timing of fluid release is not preciselycontrolled, but is known to happen at some point during use of the disk.

The previous exemplary embodiments are suitable for producing orinitiating disk activation or deactivation by modifying a feature of adata storage device at some point during a single use of the device.However, in many cases it may be desirable to produce disk deactivation(or modify the availability of certain data on the disk) after multipleuses of the data storage device. For example, a demo disk may be useablefor a fixed number of uses before it becomes unuseable, or a rental DVDcontaining a movie may be useable for a limited number of viewings.

FIG. 25 depicts an exemplary data storage device that is configured forproducing disk deactivation after a selected number of uses of the disk.One approach for detecting multiple uses of a data storage device (e.g.,for the purpose of limiting access to the data storage device after acertain number of uses) is to provide methods for modifying the diskduring normal use in such a way that structures on the disk that aremodified by use are modified in sequence over multiple uses, rather thanall being modified by a single use. This may be accomplished by settingdifferent thresholds for the different structures, and driving the diskdifferently (e.g. at a higher speed) on each subsequent use. FIG. 25illustrates, a data storage device 750 with a plurality of centrifugallyactivated fluid release devices 752, 754, 756, and 758, of the typedepicted in FIGS. 5, 6A and 6B. Fluid release device 752 includes fluidchamber 758 containing fluid 760, fluid barrier 762, and degradationsensitive region 764. Similarly, fluid release device 754 includes fluidchamber 766 containing fluid 768, fluid barrier 770, and degradationsensitive region 772, fluid release device 756 includes fluid chamber774 containing fluid 776, fluid barrier 778, and degradation sensitiveregion 780, and fluid release device 758 includes fluid chamber 782containing fluid 784, fluid barrier 786, and degradation sensitiveregion 788. Fluid release devices 752, 754, 756, and 758 may beconfigured to be activated in sequence over a number of uses of datastorage device 750. This may be accomplished by various methods. In oneembodiment, fluid barriers 762, 770, 778, and 786 may be configured tobreak at different pressures. For example, the first fluid barrier maybreak at a rotation speed obtained during normal use of the device. On asubsequent use of the device, activation of the first fluid releasedevice may be detected, and the drive may produce rotation a firstabove-normal speed of rotation for a period sufficient to activate asecond fluid release device. Similarly, on each subsequent use of thedevice, activation of at least the most recently activated fluid releasedevice may be detected, and following detection, the disk may be rotatedat a speed of rotation sufficient to activate the next fluid releasedevice. Thus, a selected number of uses of the device may be detected,until the maximum allowable number of uses has been reached, and thedisk is deactivated. The device and methodology associated with FIG. 25may be carried out with the use of a modified disk drive or drivecontroller, in order to obtain higher rotations with each used of thedisk. However, by appropriately configuring the rotation sensitivestructures on the disk, the sensitivity of each structure to rotationmay be modified by release of fluid by the preceding fluid releasemechanism. Accordingly, modification of each structure other than thefirst is dependent upon prior modification of at least one otherstructure. Modification of a first structure may modify the sensitivityof another structure by various methods, for example, by releasing afluid that dissolves a barrier to air or fluid movement, by opening orclosing an electrical circuit to produce modification of an electricallysensitive fluid barrier (e.g., formed by an electroactive polymer).

A rotation activated fluid switch capable of opening or closing anelectrical circuit can be constructed as depicted in FIGS. 26A and 26Band 27A and 27B. The fluid switch of FIGS. 26A and 26B is closed byrelease of fluid from a fluid chamber. FIG. 26A shows first chamber 500containing an electrically conductive fluid 502, which is retained inchamber 500 by barrier 504. Also shown is second chamber 506, whichincludes electrical contact 508 connected to lead 510, and electricalcontact 512 is connected to lead 514. Second chamber 506 may initiallybe filled with air or with a non-conductive fluid. When fluid 502 issubjected to a force (e.g., a centrifugal force), it may break throughbarrier 504 (to form ruptured barrier 504′) and enter second chamber506. Air vents 520 and 522 may be required to permit fluid 502 to movefrom first chamber 500 to second chamber 506. When fluid 502 fillssecond chamber 506, fluid 502 forms an electrical connection betweencontact 508 and 512, thus permitting the structure of FIGS. 26A and 26Bto function as a switch. Leads 510 and 514 may be connected to varioustypes of electronic circuitry.

FIGS. 27A and 27B depict another embodiment of a fluid activated switch,similar to that depicted in FIGS. 26A and 26B except that release offluid from the first chamber causes the switch to open rather than toclose. In FIG. 27A, a structure is provided which includes a firstchamber 600 filled with conductive fluid 602, and a barrier 604 thatprevents the flow of fluid 602 into second chamber 614. In thisembodiment, electrical contact 606, connected to lead 608, andelectrical contact 610, connected to lead 612, are located in firstchamber 600. Again, air channels 620 and 622 are provided to permit theflow of fluid from first chamber 602 to second chamber 614 when barrier604′ is broken or ruptured, as depicted in FIG. 26B. If fluid 602 is aconductive fluid, the electrical circuit (switch) between leads 608 and612 is closed when fluid 602 is contained in first chamber 600, and isopened when fluid 602 breaks through barrier 604 and moves into secondchamber 614.

Opening or closing of a switch (which may be a fluid switch or othertype of switch) may be utilized in various ways to produce modificationor degradation of data, or render data unreadable or otherwiseinaccessible. Several methods are illustrated in FIGS. 28A-28B, whichare exemplary of a larger number of methods that may be used.

FIGS. 28A and 28B illustrate blocking of reading of data by closing aswitch. A system 650, which is a portion of a data storage device suchas an optically readable disk, is shown. The data storage deviceincludes substrate layer 562 and data storage medium 654, in which isstored binary data 656. Data 656 may be read through substrate layer652, e.g., via light delivered and sensed by an optical read head.Region 658 of substrate layer 652 includes a voltage sensitive material.Lead 664 and lead 666 are connected to opposite sides regions of voltagesensitive region 658. Voltage source 660 and switch 662 are connected inseries between leads 664 and 666. When switch 662 is open, region 658 ofsubstrate 652 is in a state that permits optical reading of data 656.When switch 662 is closed (with closed configuration indicated by 662′),however, as depicted in FIG. 28B, voltage sensitive region 658transforms to a different state, indicated by reference number 658′,through which data 656 cannot be read. Voltage sensitive region 658 maybe formed, for example, from a liquid crystal or various other materialsthat are responsive to an applied voltage. Voltage source 660 mayinclude any of a number of devices or structures that are capable ofstoring or generating electrical potentials. For example, piezoelectricstructures on the disk may convert vibration or other motion in the diskto voltages. Alternatively, electrostatic charges may be accumulated onthe rotating disk. Switch 662 may be a fluid switch as depicted in FIGS.24A-25B, or may be some other type of switch.

FIGS. 29A and 29B illustrate degradation of data by closing a switch. Inthis example, a portion 670 of a data storage device is shown, whichincludes substrate layer 672 and data storage medium 674, which containsdata 676. Leads 682 and 684 are connected to opposite sides of datastorage medium 674. Current source 678 and switch 680 are connected inseries. Current source 678 may be any structure capable of generating anelectric current or capable of having an electric current induced withinit. For example, the disk may include circuitry (e.g., a conductiveloop) for generating current on the disk by induction from magneticfields produced by nearby structures, such as the drive servo motor.When the switch is in a closed state 680′, as shown in FIG. 29B, currentpasses through data storage medium 674 to convert it to degraded state674′, so that data 676 is lost. In this example, data storage medium674′ has been converted to a state in which no data values are stored.

In other cases, data stored in a data storage medium may be modified, sothat the data stored therein is readable, but does not containmeaningful or useful information. For example in FIG. 30A, a portion 690of a data storage medium is shown which includes substrate 692 and datastorage medium 694 containing data 696. Voltage source 698 and switch700 are connected in series across data storage medium 694, by means ofleads 702 and 704. When switch 700 is opened, as indicated in FIG. 30Bby reference number 700′, data stored in data storage medium 694 isconverted to modified data 696′. For example, data 696, which included apattern of logical ‘1’s and ‘0’s, may be converted to a pattern of all‘1’s or all ‘0’s, as represented by the modified data 696′.

Fluid switches as depicted in FIGS. 26A, 26B, 27A and 27B utilize fluidto open or close an electrical circuit. By replacing electrical contactswith light conductors, an optical fluid switch could be constructed,which might be used to control the exposure of a light sensitive datastorage medium to light or control additional optical circuitry on thedisk.

As discussed above, in some embodiments, it may be desirable to produceor initiate data degradation of substrate, data, or data storage mediumonly after a selected number of uses or reads of the disk have beenperformed. Various methods may be devised to track the number of times adisk or other data storage device has been used based on the state ofthe disk. In some embodiments, the disk drive may be controlledappropriately to activate a different fluid release device upon each useof the device. In other embodiments, the disk may include multiplestructures that are activated in sequence over multiple uses of thedevice, where activation of each structure facilitates activation of thenext structure.

FIG. 31 illustrates a data storage device 800 with a fluid switch thatis activatable by multiple uses. In FIG. 31, fluid chamber 802 containsa conductive fluid 804 retained by bather 806. First outward channelsegment 808 extends radially outward from fluid chamber 802 and leads tofirst distal channel segment 810. First distal channel segment 810connects to first inward channel segment 812, which lead to firstproximal channel segment 814. During a first use of data storage device800, data storage device 800 is rotated at a velocity that produces acentrifugal force in fluid 804 sufficient to break barrier 806,following which fluid 804 moves down first outward channel segment 808to first distal channel segment 810. Fluid 804 is retained in firstdistal channel segment 810 until rotation of data storage device 800decreases sufficiently, at the end of the first use. Fluid 804 thenmoves through first inward channel segment 812 to first proximal channelsegment 814, where it resides until the next use of the device. Notethat sizes and surface characteristics (hydrophilicity, hydrophobicity,etc.) of the various channel segments can be selected to promote desiredmovement of fluid in the channel segments, and that appropriateselection of channel dimensions and surface characteristics may generatecapillary forces that act in cooperation with forces generated byrotation of data storage device 800. During a second use of data storagedevice 800, fluid moves from first proximal channel segment 814, throughsecond outward channel segment 816 to second distal channel segment 818.At the end of the second use, fluid moves through second inward channelsegment 820 to second proximal channel segment 822, where it residesuntil the next use of the device. Finally, upon the third use of thedevice, fluid moves from second proximal channel segment 822, throughthird outward channel segment 824, and to third distal channel segment826. At the end of the third use, fluid moves through third inwardchannel segment 828 and into fluid chamber 830. Fluid chamber 830 mayinclude contacts 832 and 834, to form a fluid switch as describedpreviously in connection with FIGS. 26A-26B and 27A-27B. It should benoted that the dimensions of the fluid chambers and channels depicted inFIG. 31 are not exact, and that the actual dimensions of the fluidcontaining structures may be selected so that the entire fluid volumefrom fluid chamber 802 may be contained by each distal or proximalchannel segment, and, eventually, fluid chamber 830. When fluid fillsfluid chamber 830 to close the fluid switch and form a closed circuit byconnecting line 840 between electronic circuit components 836 and datastorage region 838), electronic components 836 cause a modification ofdata storage region 838. The modification may be any modification ofdata, data storage medium, or substrate, for example as described inconnection with any of FIGS. 28A-30B. In related embodiments, fluidchamber 830 may contain a degradation sensitive data storage medium thatis degradable upon exposure to a degradation inducing fluid.

As an alternative to using rotationally activated, fluid-mediatedmechanisms to produce modification to a data storage medium to renderdata unreadable or otherwise inaccessible, or to modify, destroy, orerase data, it may also be possible to use other types of rotationallyactivated mechanisms to produce modifications to a data storage device.FIGS. 32A and 32B depict a rotation activatable mechanical switch,including a cantilever made up of a beam 902 having at its end a mass904, within a chamber 906 formed in a substrate 908. Electrical contact910 is located in the wall of chamber 906 and connected to a lead 912.Electrical contact 914 is formed on mass 904 and connected to lead 916,which passes through beam 902. When mass 904 is subjected to sufficientforce, in the direction indicated by the arrow F in FIG. 32B, beam 902may flex, until contacts 910 and 914 touch to form an electricalconnection between leads 912 and 916. Leads 912 and 916 may be connectedto various electronic circuit components, to produce modification of atleast a portion of a data storage device, e.g., as described inconnection with FIGS. 28A-30B. The sensitivity of the mechanical switch,i.e., the amount of force required to close the switch, may becontrolled by selecting the mass of mass 904 and stiffness of beam 902appropriately.

FIG. 33 depicts different orientations of rotation activatablemechanical switches of the type depicted in FIGS. 32A and 32B,illustrating how different rotational forces may be used to activatesuch switches. In FIG. 33, a data storage device 950 includes a firstrotation activatable mechanical switch 952 and a second rotationactivatable mechanical switch 954. First rotation activatable mechanicalswitch 952 is oriented with mass 956 at the radial outward end of beam958, which runs in a radial direction. Beam 958 may be moved towardcontact 960 by inertial force F_(A) during angular acceleration in thedirection indicated by the arrow ω, which indicates angular velocity.F_(A) is proportional to the change in the angular velocity ω withrespect to time, dω/dt, and has a positive value when the data storagedevice is accelerating. F_(A) will be zero when the data storage deviceis rotating at a constant angular velocity, or when it is still. Duringangular deceleration, beam 958 may be moved toward contact 962, in theopposite direction of arrow ω, by inertial force F_(D). F_(D) isproportional to the change in the angular velocity ω with respect totime, dω/dt, and has a positive value when the data storage device isdecelerating. F_(D) will be zero when the data storage device isrotating at a constant angular velocity, or when it is still. Secondrotation activatable mechanical switch 954 is oriented with beam 964parallel to V_(T), the tangential velocity, and perpendicular to theradial direction. Switch 954 includes mass 966 at the end of beam 964.Second rotation activatable mechanical switch 954 may be activated whenby centrifugal force F_(C), which is proportional to the square of theangular velocity, ω². Accordingly, F_(C), will have a positive value forall non-zero values of angular velocity. By selecting the positioning ofa rotation activatable mechanical switch appropriately, the switch maybe made responsive to various combinations of forces associated withangular acceleration and centripetal acceleration (centrifugal forces).

By combining appropriately oriented rotation activatable fluid releaseand/or switching mechanisms, which may include fluid and/or mechanicalswitches, with suitable fluid or electrical circuitry, it is possible toproduce a modification (e.g., activation or deactivation) of a datastorage device in following a selected number of uses of the device.Data storage devices configured in this manner may be used in varioussystems that utilize data storage devices. FIG. 34 illustrates a system1000 configured to make use of a data storage device 1010. The systemmay be a computer system, a CD or DVD player, or various other systemswhich may make use of data storage device configured for rotatingaccess. System 1000 includes CPU (central processing unit) 1002, systemmemory 1004, one or more I/O (input/output) devices 1006, and datastorage device drive 1008. Data storage device drive 1008 may adapted toreceive a data storage device 1010. Data, power, and control signals maybe transmitted between the various system components via bus 1012.System memory 1004 may include ROM 1014 and RAM 1016. Data storagedevice drive 1008 may be controlled by device driver software 1018resident in RAM 1016. Drive interface 1020, which may include hardware,software, or firmware, may assist the transfer of signals between datastorage device drive 1008 and the rest of system 1000. The operation ofdata storage device drive 1008 may be modified or controlled at thelevel of device driver software 1018, or drive interface 1020, as wellas by modifications to data storage device drive 1008. In someembodiments, data storage device 1010 may be configured so that it willbe modified or inactivated following a selected number of uses. In someembodiments, components of system 1000 other than data storage device1010 may operate in a conventional manner. In other embodiments,selected components of system 1000 may include features that arespecialized for use with a data storage device 1010 having rotationactivatable features. System 1000 may be modified at the level of drive1008, drive interface 1020, or program code 1018 residing in RAM 1016.Drive 1008 or drive interface 1020 may be modified at the hardware,firmware, or software level. Program code 1018 may be system software orapplication program software. As discussed previously in connection withFIG. 25, system 1000 may be modified to control the speed of rotation ofdata storage device 1010 within drive 1008 to activate fluid releasedevices (or other rotation activatable mechanisms) in sequence basedupon different thresholds for activation. System 1000 may be configuredto detect prior activation of a rotation activatable mechanism on datastorage device 1010. Modifications to data storage device 1010associated with prior activate may be detected by various means. If themodification includes modification of data or modification ofaccessibility of a particular portion of data, the modification may bedetected when an attempt is made to read data from data storage device1010, e.g. by failure of reading. In some embodiments, a rotationactivatable mechanism may produce modification of a mechanical, optical,electrical, magnetic, chemical, or other property of the data storagedevice. Such modifications may be manifested as modifications of data oraccessibility of data, but are not limited to modification of data ordata accessibility. In some embodiments, modifications may be detectableby optical, electrical, magnetic, or other means, and the presence ofthe modification may serve as an instruction to the system todiscontinue reading of the disk, or to operate in a specified manner(e.g., by increasing the speed of rotation of the disk, delivering lightto a selected region of the disk, etc.).

The following flow diagrams are illustrative of various approaches thatmay be taken for controlling operation of a system as depicted in FIG.33. Some approaches make use of conventional drive operation, whileothers may make use of modifications to conventional drive operation.

FIG. 35 is a flow diagram of a method of activating a rotationactivatable control mechanism. According to various embodiments,described previously, various rotation activatable mechanisms may beused to control access to data on a data storage device, by modifying ordegrading data, or by modifying access to the data by modifying all or aportion of the data storage device. Rotation activatable mechanisms maybe rotation activatable control mechanisms. At step 1052, data is readfrom a disk (or other data storage device configured for rotatingaccess). At step 1054, the disk is rotated to activate a rotationactivatable control mechanism. A rotation activatble control mechanismmay include, for example, a rotation activatable switch or fluid releasedevice, as described previously. Because the rotation activatablecontrol mechanism is activated after data is read from the device inthis example, the use of a rotation activated control mechanism thatproduces immediate (or substantially immediate) destruction of data, orotherwise rapidly renders data unusable or inaccessible may be used.Rotation activated control mechanisms that initiate a gradual process bywhich data is destroyed or rendered inaccessible may also be used.

FIG. 36 is a flow diagram of a further exemplary method of activating arotation activatable control mechanism. At step 1102, a disk is rotatedto activate a rotation activatable control mechanism. Subsequently, atstep 1104, data is read from the disk. In this example, the rotationactivatable control mechanism may initiate a process that causes data tobe destroyed or rendered unusable or inaccessible over time. Immediatedestruction of data may be incompatible with the subsequent step ofreading data from the disk.

FIG. 37 is a flow diagram of a further exemplary method includingactivation of a rotation activatable control mechanism. At step 1152, adata storage device configured for rotating access is rotated toactivate a rotation activatable control mechanism substantiallysimultaneously with reading of data from the data storage device.

FIG. 38 is a flow diagram providing further detail of method such asthat depicted in FIG. 34. At step 1202 of FIG. 37, data is read from adisk. Reading data from the disk may including rotating the disk toselect a location on the disk from which data is to be read. At step1204, the disk is rotated to open a rotation activatable barrier.Opening a rotation activatable barrier may include rotating a disk atsubstantially the same velocity as used during reading data from thedisk, or it may include rotating the disk at a different velocity, in adifferent direction, or in some other pattern differing from therotation pattern used during reading of data from the disk. Fluid may bereleased by opening of the rotation activatable barrier, to producemodification of all or a portion of the data storage device by any ofvarious methods as described herein.

FIG. 39 is a flow diagram of a method in which a rotation activatablecontrol mechanism is used to control access to data on a disk. A processof reading data from a disk is initiated at step 1250. At decision point1252, a check is performed to determine whether a rotation activatablecontrol mechanism has been activated previously. Determination ofprevious activation of a rotation activatable control mechanism may beby various methods, as described previously, either through detectingthe inability to read data from the disk, the reading of ‘bad’ data fromthe disk, or the detecting of a modified feature of the disk. Ifprevious activation of a rotation activatable control mechanism is notdetected, process control moves to step 1254, and data is read from thedisk. After data is read from the disk, the disk is rotated to activatea rotation activatable control mechanism at step 1256. If subsequentattempts are made to read data from the disk, process control will beginagain at step 1250. When it is determined at step 1252 that the rotationactivatable control mechanism has been activated previously, the resultwill be affirmative, and the process will end (step 1258), and no datawill be read from the disk.

FIG. 40 is a flow diagram of a further embodiment of a method ofcontrolling access to data on a disk. In this exemplary embodiment,access to data on the disk is denied after a total of N accesses to thedata. After initiation of the method at step 1300, n, the number oftimes that a rotation activatable control mechanism on the disk has beenactivated, is determined at step 1302. If the disk has never beenactivated previously, zero activations will be detected. Activation of arotation activatable control mechanism may produce various types ofdetectable changes on a data storage device, including but not limitedto optically detectable changes, magnetically detectable changes,electrically detectable changes, among others. At decision point 1304,if n<N, process control moves to step 1306, where data is read from thedisk. At step 1308, the disk is rotated to activate a rotationactivatable control mechanism, increasing the number of detectablechanges on the disk by one. This is equivalent to increasing the valueof n (as represented by detectable changes on the disk) to n+1. Readingof data accomplished, the process ends at step 1310. If it is desired toread data from the disk again, the process may be repeated again,starting at step 1300. When data has been read from the disk N times, onthe (N+1)th attempt to read data from the disk, at step 1302, a value ofn=N will be obtained. At step 1304, the response to the query n<N, willbe ‘No’ and process control will jump to endpoint 1310. Thus, no furtherreads of data from the disk will be permitted. The method presented inFIG. 39 may be used, for example, in connection with a disk as shown inFIG. 25. Degradation of degradation sensitive regions 764, 772, 780, 784may be detected as an indicator of previous activation of the disk; whenall four regions have been degraded, indicating that four reads of thedisk have been performed, then no further reading of data may bepermitted. Further reading may be prevented in by configuring thesoftware controlling reading of the disk so that it will not attempt aread when all degradation sensitive regions have been degraded (even ifthe data on the disk is present and readable). Alternatively, if thedegradation sensitive regions contain information necessary for readingdata from other portions of the disk (possibly redundant copies of thesame information, or possibly different information in differentdegradation sensitive regions) when all four degradation sensitiveregions have been degraded, the information necessary for reading datafrom the disk is no longer available on the disk.

FIG. 41 is a flow diagram of a method of manufacturing a data storagedevice according to various embodiments as disclosed herein. The methodincludes the steps of: forming a substrate configured for rotatingaccess at step 1322, providing a data storage medium on said substrateat step 1324, and forming a rotation-activatable fluid release mechanismon said substrate at step 1326. The rotation-activatable fluid releasemechanism may be configured to release fluid within said data storagedevice to produce degradation of at least a portion of data stored insaid data storage device. The method may also include the steps ofstoring machine readable data in the data storage medium, and loadingthe fluid release mechanism with a fluid.

FIG. 42 is a flow diagram of a method of operating a disk drive, whichincludes the steps of adjusting the radial position of a read head withrespect to a disk received in the disk drive, as shown at step 1332;controlling the rotation of a disk received in the disk drive to permitreading of data from the disk, as shown at step 1334; reading data fromthe disk with a sensor (step 1336); and, at step 1338, controllingrotation of the disk to produce activation of a rotation sensitivestructure configured to produce degradation of data on the disk.

In some embodiments, as described above, the disk drive may beconfigured for use with rotation-sensitive disks. FIG. 43 is a flowdiagram of a method of configuring a disk drive for use with arotation-sensitive disk. The method includes a first step 1352 ofproviding read head position instructions, including commands forcontrolling the position of a read head with respect to a disk receivedin the disk drive. Next, at step 1354, motor control instructionsincluding commands for controlling rotational movement of a diskreceived in the disk drive during reading are provided. At step 1356,read instructions for managing reading of data from the disk with asensor are provided. Finally, at step 1358, data degradationinstructions are provided for controlling duration and speed of rotationof the disk at levels sufficient to induce degradation in therotation-sensitive disk. One or more of the read head positioninstructions, motor control instructions, read instructions and datadegradation instructions may be provided in the form of software,hardware or firmware. For example, instructions may be provided on adisk the is provided to a purchases of the disk drive, stored in staticor dynamic memory, or configured in an ASIC (application specificintegrated circuit) or other electronic circuitry. Memory or datastorage devices containing the instructions, or electronic circuitryembodying such instructions may be a part of the disk drive or part of acomputer or other device in which the disk drive may be installed.

With regard to the hardware and/or software used in the control ofdrives for data storage device according to the present embodiments, andparticularly to the control of data reading and disk rotation, thosehaving skill in the art will recognize that the state of the art hasprogressed to the point where there is little distinction left betweenhardware and software implementations of aspects of such systems; theuse of hardware or software is generally (but not always, in that incertain contexts the choice between hardware and software can becomesignificant) a design choice representing cost vs. efficiency orimplementation convenience tradeoffs. Those having skill in the art willappreciate that there are various vehicles by which processes and/orsystems described herein can be effected (e.g., hardware, software,and/or firmware), and that the preferred vehicle will vary with thecontext in which the processes are deployed. For example, if animplementer determines that speed and accuracy are paramount, theimplementer may opt for a hardware and/or firmware vehicle;alternatively, if flexibility is paramount, the implementer may opt fora solely software implementation; or, yet again alternatively, theimplementer may opt for some combination of hardware, software, and/orfirmware. Hence, there are several possible vehicles by which theprocesses described herein may be effected, none of which is inherentlysuperior to the other in that any vehicle to be utilized is a choicedependent upon the context in which the vehicle will be deployed and thespecific concerns (e.g., speed, flexibility, or predictability) of theimplementer, any of which may vary.

In some embodiments, portions of the subject matter described herein maybe implemented via Application Specific Integrated Circuits (ASICs),Field Programmable Gate Arrays (FPGAs), digital signal processors(DSPs), or other integrated formats. However, those skilled in the artwill recognize that some aspects of the embodiments disclosed herein, inwhole or in part, can be equivalently implemented in standard integratedcircuits, as one or more computer programs running on one or morecomputers (e.g.; as one or more programs running on one or more computersystems), as one or more programs running on one or more processors(e.g., as one or more programs running on one or more microprocessors),as firmware, or as virtually any combination thereof, and that designingthe circuitry and/or writing the code for the software and/or firmwarewould be well within the capabilities of one of skill in the art inlight of this disclosure. In addition, those skilled in the art willappreciate that certain mechanisms of the subject matter describedherein are capable of being distributed as a program product in avariety of forms, and that an illustrative embodiment of the subjectmatter described herein applies equally regardless of the particulartype of signal bearing media used to actually carry out thedistribution. Examples of a signal bearing media include, but are notlimited to, the following: recordable type media such as floppy disks,hard disk drives, CD ROMs, digital tape, and computer memory; andtransmission type media such as digital and analog communication linksusing TDM or IP based communication links (e.g., links carryingpacketized data).

In a general sense, those skilled in the art will recognize that thevarious aspects described herein which can be implemented, individuallyand/or collectively, by a wide range of hardware, software, firmware, orany combination thereof can be viewed as being composed of various typesof “electrical circuitry.” Consequently, as used herein “electricalcircuitry” includes, but is not limited to, electrical circuitry havingat least one discrete electrical circuit, electrical circuitry having atleast one integrated circuit, electrical circuitry having at least oneapplication specific integrated circuit, electrical circuitry forming ageneral purpose computing device configured by a computer program (e.g.,a general purpose computer configured by a computer program which atleast partially carries out processes and/or devices described herein,or a microprocessor configured by a computer program which at leastpartially carries out processes and/or devices described herein),electrical circuitry forming a memory device (e.g., forms of randomaccess memory), and/or electrical circuitry forming a communicationsdevice (e.g., a modem, communications switch, or optical-electricalequipment).

The foregoing detailed description has set forth various embodiments ofthe devices and/or processes via the use of block diagrams, flowcharts,and/or examples. Insofar as such block diagrams, flowcharts, and/orexamples contain one or more functions and/or operations, it will beimplicitly understood by those with skill in the art that each functionand/or operation within such block diagrams, flowcharts, or examples canbe implemented, individually and/or collectively, by a wide range ofhardware, software, firmware, or virtually any combination thereof.

Those skilled in the art will recognize that it is common within the artto describe devices for data storage and reading in the fashion setforth herein, and thereafter use standard engineering practices tointegrate such described devices and/or processes into systems includingdata storage devices as exemplified herein. That is, at least a portionof the devices and/or processes described herein can be integrated intoa system including a data storage device via a reasonable amount ofexperimentation. Those having skill in the art will recognize that suchsystems generally include one or more of a memory such as volatile andnon-volatile memory, processors such as microprocessors and digitalsignal processors, computational-supporting or -associated entities suchas operating systems, user interfaces, drivers, sensors, actuators,applications programs, one or more interaction devices, such as dataports, control systems including feedback loops and control implementingactuators (e.g., devices for sensing position and/or velocity and/oracceleration or time-rate-of-change thereof; control motors for movingand/or adjusting components and/or quantities). A typical system may beimplemented utilizing any suitable available components, such as thosetypically found in appropriate computing/communication systems and/ordata storage and reading systems, combined with standard engineeringpractices.

The foregoing-described aspects depict different components containedwithin, or connected with, different other components. It is to beunderstood that such depicted architectures are merely exemplary, andthat in fact many other architectures can be implemented which achievethe same functionality. In a conceptual sense, any arrangement ofcomponents to achieve the same functionality is effectively “associated”such that the desired functionality is achieved. Hence, any twocomponents herein combined to achieve a particular functionality can beseen as “associated with” each other such that the desired functionalityis achieved, irrespective of architectures or intermediate components.Likewise, any two components so associated can also be viewed as being“operably connected”, or “operably coupled”, to each other to achievethe desired functionality.

While particular aspects of the present subject matter described hereinhave been shown and described, it will be obvious to those skilled inthe art that, based upon the teachings herein, changes and modificationsmay be made without departing from this subject matter described hereinand its broader aspects and, therefore, the appended claims are toencompass within their scope all such changes and modifications as arewithin the true spirit and scope of this subject matter describedherein. Furthermore, it is to be understood that the invention isdefined by the appended claims. It will be understood by those withinthe art that, in general, terms used herein, and especially in theappended claims (e.g., bodies of the appended claims) are generallyintended as “open” terms (e.g., the term “including” should beinterpreted as “including but not limited to,” the term “having” shouldbe interpreted as “having at least,” the term “includes” should beinterpreted as “includes but is not limited to,” etc.). It will befurther understood by those within the art that if a specific number ofan introduced claim recitation is intended, such an intent will beexplicitly recited in the claim, and in the absence of such recitationno such intent is present. For example, as an aid to understanding, thefollowing appended claims may contain usage of the introductory phrases“at least one” and “one or more” to introduce claim recitations.However, the use of such phrases should NOT be construed to imply thatthe introduction of a claim recitation by the indefinite articles “a” or“an” limits any particular claim containing such introduced claimrecitation to inventions containing only one such recitation, even whenthe same claim includes the introductory phrases “one or more” or “atleast one” and indefinite articles such as “a” or “an” (e.g., “a” and/or“an” should typically be interpreted to mean “at least one” and/or “oneor more”); the same holds true for the use of definite articles used tointroduce claim recitations. In addition, even if a specific number ofan introduced claim recitation is explicitly recited, those skilled inthe art will recognize that such recitation should typically beinterpreted to mean at least the recited number (e.g., the barerecitation of “two recitations,” without other modifiers, typicallymeans at least two recitations, or two or more recitations).Furthermore, in those instances where a convention analogous to “atleast one of A, B, and C, etc.” is used, in general such a constructionis intended in the sense of one having skill in the art would understandthe convention (e.g., “a system having at least one of A, B, and C”would include but not be limited to systems that have A alone, B alone,C alone, A and B together, A and C together, B and C together, and/or A,B, and C together). In those instances where a convention analogous to“at least one of A, B, or C, etc.” is used, in general such aconstruction is intended in the sense of one having skill in the artwould understand the convention (e.g., “a system having at least one ofA, B, or C” would include but not be limited to systems that have Aalone, B alone, C alone, A and B together, A and C together, B and Ctogether, and/or A, B, and C together).

Although the methods, devices, systems and approaches herein have beendescribed with reference to certain preferred embodiments, otherembodiments are possible. As illustrated by the foregoing examples,various choices of system configuration may be within the scope of theinvention. As has been discussed, the choice of system configuration maydepend on the intended application of the system, the environment inwhich the system is used, cost, personal preference or other factors.Data storage device design, manufacture, and control processes may bemodified to take into account choices of system components andconfiguration, and such modifications, as known to those of skill in thearts of data storage and retrieval structures and systems, fluid controlstructures, and electronics design and construction, may fall within thescope of the invention. Therefore, the full spirit or scope of theinvention is defined by the appended claims and is not to be limited tothe specific embodiments described herein.

The invention claimed is:
 1. A method of operating a disk drive,comprising: adjusting a radial position of a read head with respect to adisk received in the disk drive; controlling a rotation of a diskreceived in the disk drive to permit reading of data from the disk;reading data from the disk with a sensor; and controlling rotation ofthe disk to produce activation of a rotation sensitive structureconfigured to produce degradation of data on the disk, includingproducing a pressure differential across a pressure-sensitive fluidbarrier sufficient to cause fluid to move through saidpressure-sensitive fluid barrier.
 2. The method of claim 1, whereincontrolling rotation of the disk to produce activation of a rotationsensitive structure configured to produce degradation of data on thedisk includes controlling rotation of the disk to produce activation ofa centrifugally activatable pressure-sensitive fluid barrier.
 3. Themethod of claim 1, wherein said pressure-sensitive fluid barrierincludes a frangible barrier.
 4. The method of claim 1, wherein saidpressure-sensitive fluid barrier includes a capillary break, hydrophobicbreak, or hydrophobic valve.
 5. The method of claim 1, whereincontrolling rotation of the disk to produce activation of a rotationsensitive structure configured to produce degradation of data on thedisk includes controlling rotation of the disk to produce release of aconductive fluid from a fluid release mechanism to open a fluid switch,wherein opening the fluid switch opens an electrical circuit on thedisk.
 6. The method of claim 1, wherein controlling rotation of the diskto produce activation of a rotation sensitive structure configured toproduce degradation of data on the disk includes controlling rotation ofthe disk to produce release of a conductive fluid from a fluid releasemechanism to close a fluid switch, wherein opening the fluid switchcloses an electrical circuit on the disk.
 7. The method of claim 1,wherein controlling rotation of the disk to produce activation of arotation sensitive structure configured to produce degradation of dataon the disk includes controlling rotation of the disk to release a fluidinto a region of the disk containing said data, wherein said fluidrenders said data unusable or unreadable.
 8. The method of claim 1,wherein the pressure-sensitive fluid barrier includes a capillary break.9. The method of claim 1, wherein the pressure-sensitive fluid barrierincludes a hydrophobic break.
 10. The method of claim 1, wherein thepressure-sensitive fluid barrier includes a hydrophobic valve.
 11. Amethod of operating a disk drive, comprising: adjusting a radialposition of a read head with respect to a disk received in the diskdrive; controlling a rotation of a disk received in the disk drive topermit reading of data from the disk; reading data from the disk with asensor; and controlling rotation of the disk to produce activation of arotation sensitive structure configured to produce degradation of dataon the disk, the rotation sensitive structure including amicromechanical valve.
 12. The method of claim 11, wherein controllingrotation of the disk to produce activation of a rotation sensitivestructure configured to produce degradation of data on the disk includescontrolling rotation of the disk to produce activation of acentrifugally activatable micromechanical valve.
 13. The method of claim11, wherein controlling rotation of the disk to produce activation of arotation sensitive structure configured to produce degradation of dataon the disk includes controlling rotation of the disk to produce releaseof a conductive fluid from a fluid release mechanism to open a fluidswitch, wherein opening the fluid switch opens an electrical circuit onthe disk.
 14. The method of claim 11, wherein controlling rotation ofthe disk to produce activation of a rotation sensitive structureconfigured to produce degradation of data on the disk includescontrolling rotation of the disk to produce release of a conductivefluid from a fluid release mechanism to close a fluid switch, whereinopening the fluid switch closes an electrical circuit on the disk. 15.The method of claim 11, wherein controlling rotation of the disk toproduce activation of a rotation sensitive structure configured toproduce degradation of data on the disk includes controlling rotation ofthe disk to release a fluid into a region of the disk containing saiddata, wherein said fluid renders said data unusable or unreadable.
 16. Amethod of operating a disk drive, comprising: controlling a rotation ofa disk received in the disk drive to permit reading of data from thedisk, the disk including a fluid release mechanism including fluidcontained within a fluid chamber on the disk and a pressure sensitivefluid barrier having a selected orientation and break pressure; readingdata from the disk with a sensor; and controlling rotation of the diskto produce a pressure differential across the pressure-sensitive fluidbarrier sufficient to cause fluid to move through the pressure-sensitivefluid barrier to produce degradation of at least a portion of the datastored on the disk; wherein the reading data from the disk with a sensorand controlling rotation of the disk to produce a pressure differentialacross the pressure-sensitive fluid barrier sufficient to cause fluid tomove through the pressure-sensitive fluid barrier to produce degradationof at least a portion of the data stored on the disk are timed such thatdegradation of the at least a portion of the data stored on the diskoccurs after the at least a portion of the data has been read from thedisk with the sensor.
 17. The method of claim 16, wherein the readingdata from the disk with a sensor is performed prior to the controllingrotation of the disk to produce a pressure differential across thepressure-sensitive fluid barrier sufficient to cause fluid to movethrough the pressure-sensitive fluid barrier to produce degradation ofat least a portion of the data stored on the disk.
 18. The method ofclaim 16, wherein the reading data from the disk with a sensor isperformed following the controlling rotation of the disk to produce apressure differential across the pressure-sensitive fluid barriersufficient to cause fluid to move through the pressure-sensitive fluidbarrier to produce degradation of the at least a portion of the datastored on the disk, the fluid producing degradation of the at least aportion of the data stored on the disk over a period of time.
 19. Themethod of claim 16, wherein the reading data from the disk with a sensoris performed simultaneously with the controlling rotation of the disk toproduce a pressure differential across the pressure-sensitive fluidbarrier sufficient to cause fluid to move through the pressure-sensitivefluid barrier to produce degradation of at least a portion of the datastored on the disk.